Investigating the Structural, Spectroscopic, and Electrochemical Properties of [Fe{(EPiPr₂)₂N}₂] (E = S, Se) and the Formation of Iron Selenides by Chemical Vapor Deposition

Abstract

The anionic L = [(EPiPr2)2N]– (E = S, Se) form of the dichalcogenidoimidodiphosphinato‐type ligands containing iPr peripheral groups has been shown previously to afford tetrahedral [MIIL2] complexes (E = S, M = Mn, Co, Ni, Zn; E = Se, M = Co, Ni, Zn). The syntheses of the analogous [FeL2] complexes [E = S (1), Se (2)] were performed in this work through metathesis reactions between FeCl2 and the corresponding KL salts. For both 1 and 2, X‐ray crystallography revealed two distinct molecules in the asymmetric unit. Complexes 1 and 2 are isostructural and exhibit P–E and P–N bond‐length differences compared with those of the free ligands, and these differences are translated into shifts of the corresponding IR bands. Cyclic voltammetry studies showed that the FeII → FeIII oxidation in 2 occurs at a lower potential than that of 1. The zero‐field Mössbauer spectra of the two complexes are quite similar and provide evidence of similar S = 2 electronic structures. The observation of crystallographically distinct FeIIE4 sites for both 1 and 2 is also revealed in the corresponding Mössbauer spectra. Complex 2 was employed as a single‐source precursor in catalyst‐aided chemical vapor deposition experiments, which afforded the iron selenides FeSe and Fe3Se4.

The [Fe{(SePPh2)2N}2] Complex Revisited: X‐ray Crystallography, Magnetometry, High‐Frequency EPR, and Mössbauer Studies Reveal Its Tetrahedral FeIISe4 Coordination Sphere

“…The average value of the four non‐equivalent Fe–Se bond lengths of complex 1 is 2.48 Å (Table ), which is within the corresponding values observed for tetrahedral Fe II Se 4 ‐containing complexes identified in the CSD: [N(CH 3 CH 2 ) 4 ] 2 [Fe(SePh) 4 ] (2.46 Å), [Fe(1,10‐phen) 3 ][Fe(SePh) 4 ] (2.46 Å), [PPh 4 ] 2 [Fe(Se 4 ) 2 ] (2.45/2.43 Å), [N(CH 3 ) 4 ] 2 [Fe{SeC(CH 3 ) 3 } 4 ] (2.47 Å), [bis(1,3‐di‐ tert ‐butyl‐1 H ‐imidazol‐3‐ium)] 2 [Fe(SePh) 4 ] (2.45 Å), [Fe{(SeP i Pr 2 ) 2 N} 2 ] (2.47 Å) and [Fe(dmise) 4 ][BF 4 ] 2 , dmise = N , N′ ‐dimethylimidazoleselone (2.46 Å) . The recently reported structure of 1 SP surprisingly contains a square planar FeSe 4 coordination sphere .…”

“…The FeSe 4 core of complex 1 exhibits a distorted tetrahedral geometry, as reflected by the magnitude of the Se–Fe–Se angles which lie between 101.7(1)° and 115.7(1)° (Table S2). The two endocyclic Se–Fe–Se bite angles amount to 115.7(1)° and are similar to those of the [Fe{(SeP i Pr 2 ) 2 N} 2 ] and [M{(SePPh 2 ) 2 N} 2 ], M = Mn, Co, Zn, complexes listed in Table . The dihedral angle between the planes defined by the endocyclic Se–Fe–Se angles of complex 1 is 86.8°, comparable to those of the [M{(SePPh 2 ) 2 N} 2 ], M = Mn, Co, Zn, complexes (Table ).…”

“…With respect to the coordination of [Ph 2 P(Se)NP(Se)Ph 2 ] – to Fe II , it should first be noted that the following literature complexes have been shown, by X‐ray crystallography, to unequivocally contain a tetrahedral FeSe 4 coordination sphere: [N(CH 3 CH 2 ) 4 ] 2 [Fe(SePh) 4 ], [Fe(1,10‐phen) 3 ][Fe(SePh) 4 ], [PPh 4 ] 2 [Fe(Se 4 ) 2 ], [N(CH 3 ) 4 ] 2 [Fe{SeC(CH 3 ) 3 } 4 ], [bis(1,3‐di‐ tert ‐butyl‐1 H ‐imidazol‐3‐ium)] 2 [Fe(SePh) 4 ], [Fe{(SeP i Pr 2 ) 2 N} 2 ] and [Fe(dmise) 4 ][BF 4 ] 2 , dmise = N , N′ ‐dimethylimidazoleselone . In addition, on the basis of spectroscopic and room temperature magnetometry studies, the [Fe{(SePPh 2 ) 2 CH} 2 ] complex, bearing a ligand which is similar to L, has been proposed to also contain a tetrahedral FeSe 4 core .…”

“…The magnetic and spectroscopic properties of 1 were investigated by magnetometry, as well as by IR, high‐frequency EPR and Mössbauer spectroscopy. Comparisons are being made with the properties of 1 SP , [Fe{(SeP i Pr 2 ) 2 N} 2 ] and [Fe{(SPPh 2 ) 2 N} 2 ] complexes. Recent high‐frequency EPR studies of the latter have revealed distinct S = 2 Fe II sites, the spin‐Hamiltonian parameters of which have been accurately determined.…”

Investigating the Structural, Spectroscopic, and Electrochemical Properties of [Fe{(EPiPr2)2N}2] (E = S, Se) and the Formation of Iron Selenides by Chemical Vapor Deposition

“…The affiliation assignments for two of the authors (G. R. and P. P.) in the original article are incorrect; the correct links are given in this Correction .…”